It is a relatively new finding that there is a vast radiation of Triculini snails (Pomatiopsidae: Triculinae) throughout southern China actually or potentially transmitting Schistosoma and Paragonimus. The objectives here are to continue pursuing systematic, phylogenetic and biogeographic studies of Chinese Triculinae and to use the snail phylogenies to assess the patterns of co-evolution of Schistosoma and Paragonimus with these snails. The studies will involve detailed comparative anatomy, molecular genetic (allozyme population genetics and LrRNA sequencing), and biogeography. The work links to previous work done on the phylogeny of Triculinae in S.E. Asia and India. The systematics work in China is in its infancy as detailed comparative anatomical data are now available for only 17% of the Chinese Triculinae estimated to be >140 species, >12 genera. With each excursion into the provinces, new genera, and species involved in transmitting these two parasite genera are found. Work in cooperation with the Institute of Parasitic Diseases in Shanghai and Hangchow, with the Academia Sinica, Beijing and with Hubei Medical College. Collaborative work in Hangchow is synchronized with their ongoing work on Paragonimus. We will initiate allozyme molecular genetic work on Triculinae in Hangchow. Collaborative work in Shanghai is synchronized our ongoing work on the molecular genetics of Oncomelania (Pomatiopsidae: Pomatiopsinae) throughout China relative to regional genetic differentiation of Schistosoma japonicum.